Stream sniping is when someone watches your stream to get an upper hand to essentially cheat against you in a game. For example, they could find your position on an open-worldmap, find out where your base is, or even find out when you're low on health, so they can ambush you. It sucks. The deveopers of Rust, Facepunch Studios... are (to my knowledge), the first game developers to build a preventative measure against it into their game. They call it Streamer Mode.
Hey, its Edward Longface again! Ahhhh!!! Why did he shoot at me?! He probably knew my plan. He must be streamsniping!
to follow a person who is streaming gameplay footage (usually on twitch or ustream) into the same games, using their stream to find and harass them (often for hilarious results.)
"Do a can crush for Jay Owens in 30 seconds or you will be shot.... Oh my god, it's the same guy! He's stream sniping me!"
One who watches a Fortnite stream, usually on twitch or mixer, ques up in the same game, kills the streamer and taunts them in some way to get attention.
Pajama casual is a term used when working from home and preparing for a video conference. All business above the waist and your pajama pants down below.